The present invention relates generally to systems, arrangements and methods for tracking the position of and/or guiding an underground boring tool during its operation and more particularly to tracking the position of the boring tool within a coordinate system using magnetic field intensity measurements either alone or in combination with certain physically measurable parameters. Positional information may then be used in remotely guiding the boring tool.
As will be described in more detail hereinafter, there are disclosed herein portable mapping tool arrangements and associated methods for use in a horizontal drilling system. The portable mapping tool includes a boring tool configured for transmitting a locating signal and at least one electromagnetic field detector which is configured for measuring the locating signal from a fixed position proximate to the surface of the ground in a drilling area. In one embodiment, the mapping tool includes a housing and a transmitter arrangement supported by the housing for transmitting a setup locating signal for reception by the detector in the region for use in determining certain initial conditions at least prior to drilling.
The certain initial conditions may include the position of the detector in the region. The detector may be positioned at a known location on the surface of the ground at the fixed position and the certain initial conditions may include an unknown position of the portable mapping tool at another location in the region relative to the detector at the known location.
The portable mapping tool may include at least a first detector and a second detector at respective first and second spaced apart positions on the surface of the ground and wherein the certain initial conditions include the second position of the second detector relative to the first position of the first detector. Alternatively, the portable mapping tool may include a drill rig for actuating the boring tool from a drilling position in the region and the certain initial conditions include the drilling position relative to an at least temporarily fixed position of the portable mapping tool in the region.
In another embodiment, the locating signal transmitted by the boring tool is a first dipole field and the setup locating signal transmitted by the portable mapping tool is a second dipole field.
In another embodiment, the portable mapping tool includes a positioning arrangement cooperating with the housing for positioning the mapping tool, at least temporarily, on the detector in a predetermined way such that the orientation of the mapping tool is fixed relative to the detector on which it is positioned. The positioning arrangement includes an indexing configuration for engaging the detector in the predetermined way to temporarily fixedly maintain the orientation of the portable mapping tool relative to the detector. The indexing configuration includes a plurality of indexing pins in a configuration for engaging the detector in the predetermined way to temporarily fixedly maintain the orintation of the portable mapping tool relative to the detector.
The portable mapping tool may further include an arrangement within the housing for determining certain orientation parameters when the mapping tool is engaged with the detector. In one version, this orientation determining arrangement of the mapping tool includes a configuration for determining the magnetic orientation of the mapping tool and, thereby, the magnetic orientation of the detector when engaged therewith. This configuration may include a magnetometer and/or a tilt sensing arrangement for determining the tilt of the mapping tool and, thereby, the tilt of the detector when engaged therewith.
In other embodiments, the portable mapping tool may include a processing section remote from the portable mapping tool. In this case, the portable mapping tool may include a telemetry arrangement for transferring the certain orientation parameters to the processing section. Various embodiments of the portable mapping tool may also include a display arrangement for displaying the certain orientation parameters.